1. Technical Field of the Invention
This invention relates to compositions for and methods of treating materials containing components which can be dispersed upon being contacted with an oil. This invention further relates to dispersing materials comprised of hydrocarbons and hydrocarbon residues by contacting the materials with a composition containing at least one ester of a fixed oil. This invention still further relates to removing solid deposits comprised of or derived from petroleum base components from a surface by contacting the deposits with a composition which contains a modified vegetable oil comprised of esters of fatty acids.
2. Description of the Prior Art and Problems Solved
It is known that materials containing hydrocarbons can be dispersed by contacting the materials with a wide variety of liquid cleaning formulations comprised of liquid hydrocarbons derived from petroleum. Such liquid hydrocarbons have been variously referred to in the chemical cleaning art as extractants, dispersants and solvents. The liquid cleaning formulations have ranged from substantially 100 percent oil formulations to combinations of oil and water including oil external/aqueous internal emulsions and aqueous external/oil internal emulsions. Accordingly, methods are known in the art for removing materials comprised of hydrocarbon oil, bitumens, asphalts, tar, hydrocarbon residues and similar petroleum based materials from a surface to which they adhere by contacting the materials with a cleaning formulation which includes a liquid hydrocarbon solvent, dispersant or extractant.
For purposes of this invention the phrase hydrocarbon components shall mean hydrocarbon oil, paraffins, bitumens, asphalts, tar, hydrocarbon residues and other petroleum based materials. The hydrocarbon components to be treated in accordance with the methods of this invention can occur in the liquid phase, the solid phase or some mixture of liquid and solid and ordinarily adhere to a substrate surface, such as metal, stone, concrete or paint, from which the hydrocarbon component is to be removed. Accordingly, the hydrocarbon components are variously referred to herein, and in the art, as deposits, contaminants, adherents and foulants.
The removal of deposits containing hydrocarbon components from a surface, such as a metal surface, is disclosed in U.S. Pat. Nos. 5,356,482, 5,389,156 and 5,425,814. Each of these patents disclose methods of and compositions for cleaning vessels employed in the refining and chemical processing of hydrocarbon feedstocks, such as crude petroleum oil. These patents discuss methods employed in the prior art to remove deposits from metal surfaces wherein the methods feature the use of conventional light hydrocarbon solvents in separate and successive deposit contacting steps and degassing steps. The steps are employed to remove deposits from the interiors of vessels and to enable workers to safely enter the vessels for inspection and internal mechanical repairs thereof.
With the prior art background in mind, the mentioned patents disclose a xe2x80x9cunitary processxe2x80x9d of simultaneous deposit removal and degassing featuring the use of terpenes, a specific class of hydrocarbon found in resins and volatile oils, which are also called xe2x80x9cessentialxe2x80x9d oils. The patents are specifically concerned with a specific terpene, d-limonene, which naturally occurs in lemon peel, orange oil and pine needles. The patents disclose that d-limonene not only removes the usual hydrocarbon components, but also removes dangerous volatile organic contamination as well as benzene, which the patents disclose as being a known health hazard.
For purposes of definition, it is noted that an xe2x80x9cessential oilxe2x80x9d is any of a class of volatile, water insoluble oil that imparts the characteristic odors to plants. Essential oils are used in perfumes and flavorings. In contrast, a xe2x80x9cfixed oilxe2x80x9d is a nonvolatile, water insoluble oil, especially a fatty oil, such as vegetable oil.
In accordance with the above known methods, the deposits comprised of hydrocarbon components are contacted by the cleaning formulations for a time and at a temperature sufficient to cause the mentioned hydrocarbon components of the deposits to soften, disperse or dissolve to thereby enable removal of the deposits by liquid flushing, circulation, mechanical action or some combination thereof.
The cleaning formulations used in the known methods include hydrocarbons such as light cycle oil, heavy gas oil, diesel oil, kerosene and terpenes, such as d-limonene.
Petroleum hydrocarbon chemical solvents currently employed in prior art cleaning formulations, while performing satisfactorily from a cleaning point of view, contain compounds, broadly referred to herein as xe2x80x9cproblem compounds,xe2x80x9d which render use of the prior art solvents unsatisfactory from an environmental and personal health point of view. The problem compounds include volatile organic compounds, called VOCS, as well as other toxic and potentially carcinogenic materials, such as, benzene and methyl tertiary butyl ether. These problem compounds are known to cause eye and skin irritation and to be a source of water pollution. Furthermore, the problem compounds are not biodegradable.
Some cleaning methods involve treating the interiors of large vessels with a chemical cleaning formulation followed by entry of personnel into the treated interiors. It is, accordingly, clear that the use of the prior art petroleum solvents to clean such vessels, followed by personnel entry into the interiors thereof, requires extensive and time-consuming, post-cleaning operations, such as water flushing and steaming, to remove the problem compounds from the vessel interiors.
In view of the above, it is highly desirable, from an operational point of view, to employ a cleaning composition which will satisfactorily remove hydrocarbon components from a surface; which does not include volatile organic compounds, or other toxic and potentially carcinogenic materials, such as, benzene; which does exhibit sufficiently high flash and flame points to minimize explosion and fire hazards encountered during cleaning operations; which, because of its chemical nature, is biodegradable; which has a low chemical and biological oxygen demand; which will not be a source of environmental damage; and which will not present waste disposal problems.
In addition to the above, a desirable result of a chemical cleaning service is the absence of an oil film on the surface cleaned, such as a metal surface, at the conclusion of the cleaning process. It is thought that an oil-wet surface merely attracts and traps air-borne particles which serve to soil an otherwise clean surface. Accordingly, still another desirable feature of a cleaning composition employed to remove hydrocarbon components from a surface is that the composition operate to provide a cleaned surface that is water-wet and not oil-wet.
Furthermore, it is also desirable that the process of removing deposits comprised of hydrocarbon components from a surface be conducted by contacting the deposits with a relatively low concentration of chemical cleaning composition wherein the contact can be effectively conducted by use of an aqueous carrier. It is still further desirable to enable separation of the used cleaning composition, the removed hydrocarbon components and the aqueous carrier to facilitate disposal subsequent to the conclusion of the cleaning process.